This invention relates to a proximity sensor for detecting the presence of or counting articles, and more particularly, to an infrared proximity sensor for detecting the presence of or counting seeds in a container or as they pass through a chute.
In many situations, it is necessary to detect the presence of an article in a container or to count the number of articles passing through a chute, tube or passageway. The detection and counting of articles is particularly important in agriculture, e.g., when planting seeds. In the modern agricultural setting, the farmer uses a planting machine to plant seeds in the soil. Such a machine generally includes a container for holding the seeds to be planted, and also includes at least one tube or chute, through which the seeds travel before being placed into the soil. It is desirable and necessary to detect the presence of seeds in the container or to count the number of seeds passing through the chute on their way to being planted in the soil. By being able to detect the presence of seeds in the container, the farmer is able to automatically determine when the seed-holding container is empty, and thus determine when the container needs to be refilled with more seed. Similarly, by being able to detect and/or count the seeds as they travel through the chute, the farmer is able to count the number, and frequency at which, the seeds are being planted and also detect if a blockage has occurred that is interfering with the seed planting process.
The use of detection and/or counting devices in the agricultural setting is generally known. These devices, however, use light beam-breaking technology to detect and/or count seeds. Specifically, these devices generally use an optical emitter, such as a light emitting diode (LED), positioned across from an optical detector, such as a photodiode. For example, the LED is attached to one wall of the container or the chute, and the photodiode is attached to the opposite wall of the container or the chute. The photodiode detects the light that is emitted by the LED. When a seed travels between the LED and the photodiode, the beam of light is interrupted. This interruption is generally interpreted by the detector as a seed (or other article that is to be detected). U.S. Pat. No. 4,268,825 to Kaplan, U.S. Pat. No. 5,635,911 to Landers et al., and U.S. Pat. No. 4,634,855 to Friend et al. are representative references that teach the use of such technology to detect and count the presence of seeds in a container or as they pass through a chute.
The use of light beam-breaking technology to detect and/or count seeds in a container and/or chute has several distinct disadvantages and shortcomings. As stated above, the emitter and the detector must be placed opposite one another and are usually attached to opposite walls of a container. In many instances, however, it is not possible to place the emitter and detector on opposite walls of a container because, for example, the seed holding container in the seed planting machine may include moving parts inside or on its walls such that only one wall is available for attaching sensor devices. Because the emitter and the detector must be placed across from one another, it is impractical or impossible to place a beam-breaking-type article counting/detecting device in such a container.
Another disadvantage of the known article counting devices is the complexity of such devices. Because the emitter and the detector are placed on opposite sides of a container or a chute, the two devices must somehow be connected to one another and/or to additional circuit components, usually by a wire. Physically connecting the emitter and the detector once they have been placed on the opposite sides of the container and/or chute requires extra manufacturing effort and increases production costs. Additionally, the extra wiring makes installation more difficult and increases the risk of damage to the detecting device, which increases warranty and repair costs. For example, the extra wiring connecting the emitter to the detector is easy to snag and break during shipping, handling and use. Thus, extra effort must be expended to protect the wires. Additionally, if a user needs to replace the emitter and/or detector, the user must be extra cautious to prevent inadvertent damage to the wires connecting the emitter to the detector.
Available commercially are infrared (IR) reflective detector products, which consist of an emitter, a detector and associated circuitry within a single package (referred to as a xe2x80x9cphoto/reflective pairxe2x80x9d). With these products, infrared light emitted by the emitter is detected by the detector after having been reflected by an object. These products can detect various articles and can be incorporated into larger and more complex circuit designs. It has been found, however, that these off-the-shelf, reflective detector products are incapable of detecting all the different sizes and speeds that are used in agriculture (e.g., canola seeds traveling at 30 miles per hour) and also are incapable of detecting seeds that are in close proximity to or immediately in front of the emitter or the detector.
In view of the foregoing, it is a general aim of the present invention to provide a proximity sensor that is capable of detecting and/or counting articles in a container or passing through a chute in which an emitter and a detector do not have to be located opposite one another.
It is another object of the invention to provide a proximity sensor capable of detecting and/or counting articles in a container or passing through a chute that uses infrared technology.
Yet another object of the invention is to provide a proximity sensor that uses an infrared emitter and an infrared detector that is capable of detecting and/or counting any size and shape seed used in agriculture that is in a container or passing through a chute.
It is a feature of the invention to provide a proximity sensor that is capable of detecting and/or counting articles in a container or passing through a chute in which an emitter and a detector can be located on a single printed circuit board.
Another object of the invention is to provide a proximity sensor that is capable of detecting and/or counting articles in a container or passing through a chute even when the article is located immediately in front of the emitter and/or detector.
A further object of the present invention is to provide a proximity sensor that is capable of detecting and/or counting articles in a container or passing through a chute when the detector and the emitter are separated from the articles by a non-focusing lens.
It is a more particular object of the invention to provide a proximity sensor the performance of which is not affected by the presence of sunlight or fluorescent light sources.
Yet another object of the present invention is to provide a proximity sensor that is capable of using a focusing lens to increase the detection range of the device without increasing the power requirements of the device.
A specific object of the present invention is to provide a detector for detecting the presence of seeds in a container which relies on infrared light and therefore is not affect by moisture.
It is another object of the present invention to provide a proximity sensor in which the detection range and the size and shape of the articles that can be counted and/or detected can be varied by varying the distance and/or angle between the emitter and the detector and/or by changing the frequency of the wavelengths that are emitted or detected.
These and other objects and features are achieved according to the present invention, in which infrared (IR) technology is used to detect and/or count seeds in a container or passing through a chute. An infrared light emitting diode (IR emitter) and an infrared photodiode or infrared phototransistor (IR detector) are placed on a single printed circuit board (pcb). A seed or other article that is in front of, or passes by, the IR emitter will reflect some or all of the radiation from the emitter. The IR detector will detect some or all of the reflected radiation and provides an output that can be interpreted as a count or the presence of a seed or other article. By placing all the components of the detector on a single pcb, one is able to manufacture a self-contained device which can be placed in a container even when the container only has one wall available for placing sensors. Additionally, the above mentioned disadvantages associated with having to run a wire between the emitter and the detector are eliminated. The detector of the present invention, therefore, is easier and less expensive to produce and is less likely to be damaged or require repair or replacement.
Furthermore, the present invention includes a proximity sensor with an emitter capable of emitting energy waves of a selected wavelength and a detector in close proximity to the emitter capable of detecting energy waves with the selected wavelength. The proximity sensor also includes a phase lock loop integrated circuit for driving the emitter at a preselected frequency. When an article to be detected passes the proximity sensor, the energy waves emitted by the emitter are reflected off the article and detected by the detector. As a result of detecting the energy waves with the selected wavelength, the detector outputs a signal which is modulated at the same preselected frequency as the output of the emitter. When the frequency of the output signal received from the detector matches the frequency at which the emitter is driven, the phase lock loop integrated circuit outputs a signal that may be used by a monitoring device to detect, count and/or monitor the articles.
Other objects and advantages will become apparent from the following detailed description when taken in conjunction with the drawings, in which: